Revision 09d07554 docs/admin-guide.rst

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Synnefo allocates all his/hers VMs to the specific backend in the variable,
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even if is marked as drained (useful for testing).
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Allocation based on disk-templates
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**********************************
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Besides the available resources of each Ganeti backend, the allocator takes
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into consideration the disk template of the instance when trying to allocate it
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to a Ganeti backend. Specifically, the allocator checks if the flavor of the
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instance belongs to the available disk templates of each Ganeti backend.
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A Ganeti cluster has a list of enabled disk templates
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(`--enabled-disk-templates`) and a list of allowed disk templates for new
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instances (`--ipolicy-disk-templates`). See the `gnt-cluster` manpage for more
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details about these options.
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When Synnefo allocates an instance, it checks whether the disk template of the
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new instance belongs both in the enabled and ipolicy disk templates. You can
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see the list of the available disk-templates by running `snf-manage
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backend-list`. This list should be updated automatically after changing
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these options in Ganeti and it can also be updated by running `snf-manage
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backend-update-status`.
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So the administrator, can route instances on different backends based on their
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flavor disk template, by modifying the enabled or ipolicy disk templates of
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each backend.  Also, the administrator can route instances between different
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nodes of the same Ganeti backend, by modifying the same options at the
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nodegroup level (see `gnt-group` manpage for mor details).
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Managing Virtual Machines
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~~~~~~~~~~~~~~~~~~~~~~~~~
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